Professor Gillian Foulger, Earth Sciences, wins Royal Astronomical Society’s Price Medal.

(19 October 2005)

The Price Medal is usually awarded every other year, for investigations of outstanding merit in solid-earth geophysics, oceanography, or planetary sciences. Professor Gillian Foulger’s research has raised serious doubts about the nature of the hotspots beneath volcanic centres such as Iceland, Hawaii and Yellowstone. Professor Foulger’s research on Iceland and other hotspots has led to a major rethinking of a pillar of modern geophysics, that until recently widely held the view that hotspots, regions of long-lived excess volcanism such as Iceland, Hawaii, or Yellowstone, result from plumes of hot material upwelling from great depth in the mantle. In the plume model, plate motion over fixed or slow-moving plumes causes age-progressive linear volcanic chains and topographic swells that identify plumes and yield inferences about their properties. This model has been widely accepted because it gives an elegant explanation of how diverse volcanic regions have similar origins, and absolute reference frame describing plate motions relative to the deep mantle, and implies an important mode of mantle convection with major implications for the Earth’s thermal and chemical evolution. However, Foulger’s work has raised serious doubts about the model, especially in Iceland. She has made a strong case that the low velocity material is restricted to the upper mantle, and that the island’s great volcanic thickness is not due to melting at high temperatures, but instead due to melting of mantle that produces an unusually high melt fraction. In her model, Iceland results from excess magmatism as the ridge migrates over the Caledonian suture, containing rocks remaining from an earlier subduction period. These arguments – which at first seem surprising – have been supported by other studies. She has also been involved in studies of Yellowstone which find even stronger evidence that the volcanism does not result from a deep mantle plume. Foulger has taken the lead in a multidisciplinary reassessment of these issues via many publications, summarized in her recent (2002) paper in Astronomy and Geophysics and her website www.mantleplumes.org. She has organised international conferences and edited an upcoming GSA volume. These efforts have made the plume controversy one of the “hottest” topics in global geophysics. However all this plays out, her creativity, energy and willingness to tackle a complex multidisciplinary issue will have a major impact on geophysics for years to come.